自定义迭代器 [英] custom iterator
问题描述
我正在实现一个自定义迭代器（随机访问类型）所以我可以使用
stl算法，比如对我的遗产进行排序容器。然而，我正在编译
问题。当我实现我的customIterator类时，我已经定义了下面的运算符（以及其他人，但他们现在不是很重要的，我不认为）。
class customIterator
{
customerIterator& operator *（）const;
int operator-（const customIterator& x）;
int operator-（const contIter& rhs）const
customIterator&安培; operator ++（）;
customIterator operator ++（int）;
customIterator& operator - （）;
customIterator operator - （int）;
customIterator& operator + =（difference_type n）;
customIterator& operator - =（difference_type n）;
customIterator operator +（difference_type rhs）const;
customIterator operator-（difference_type rhs）const;
int& ; operator []（int n）;
bool operator ==（const customIterator& x）const;
bool operator<（const customIterator& x）const;
}
问题是当我将其中一个迭代器传递给
std :: sort时，我很想念所有各种运算符，如运算符>（int），
运算符/（int），运算符 - （int）。
这些是生成的，因为stl： ：在我的平台上排序有代码
像这样;
while（__last - __first> __stl_threshold）{
或使用类似的表达式;
如果（（__last - __first）/ 2>某事......）
我需要吗？提供一个操作符，用于将我的
customIterator隐式转换为int，以便可以评估比较（__last - first>
__stl_threshold）？
现在我只是想用一个简单的案例来编译这个元素
向量的向量。
std ::矢量<诠释> vint;
containerWrapper包装器（vint）;
customIterator begin = wrapper.begin（）;
customIterator end = wrapper。结束（）;
//这里的编译错误.......
std :: sort（开始，结束，aCompareFunction（））;
编译错误就像;
1）运算符>没有在参数类型customIterator中实现
类型为int
2）operator ==未在参数类型customIterator中实现
类型int
3）运算符/未在类型customIterator中实现参数
类型为int
等。等等
任何想法？
谢谢。
Hi,
I''m implementing a custom iterator (random access type ) so I can use
stl algorithms such as sort on my legacy containers. I''m having
problems compiling however. when implementing my customIterator class I
have defined the operators below (as well as others but they''re not
important right now, I don''t think).
class customIterator
{
customerIterator& operator*() const;
int operator-(const customIterator& x);
int operator-(const contIter& rhs) const
customIterator& operator++();
customIterator operator++(int);
customIterator& operator--();
customIterator operator--(int);
customIterator& operator+=(difference_type n);
customIterator& operator-=(difference_type n);
customIterator operator+(difference_type rhs) const;
customIterator operator-(difference_type rhs) const;
int& operator[](int n);
bool operator==(const customIterator& x) const;
bool operator<(const customIterator& x) const;
}
The problem is when I come to pass one of these iterators into
std::sort, I''m missing all sorts of operators like operator>(int),
operator/(int), operator-(int).
These are being generated because the stl::sort on my platform has code
like this;
while (__last - __first > __stl_threshold) {
or uses expressions like;
if ( (__last - __first)/2 > something... )
Do I need to provide an operator for implicit conversion of my
customIterator to an int so that the comparison ( __last - first >
__stl_threshold) can be evaluated?
Right now I''m just trying to get this to compile with a simple case
vectors of ints.
std::vector<int> vint;
containerWrapper wrapper(vint);
customIterator begin = wrapper.begin();
customIterator end = wrapper.end();
// compilation errors here .......
std::sort(begin, end, aCompareFunction());
compilation errors are like;
1) operator> not implemented in the type customIterator for arguments
of type int
2) operator== not implemented in the type customIterator for arguments
of type int
3) operator/ not implemented in the type customIterator for arguments
of type int
etc. etc.
any ideas?
thanks.
推荐答案
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新闻：11 ********************* @ g49g2000cwa.googlegro ups.com ...
[...]
"Gr*****@nospam.com" <Gr**********@gmail.com> schrieb im Newsbeitrag
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[...]
class customIterator
{
[...]}
[...] //这里的编译错误... ....
std :: sort（begin，end，aCompareFunction（））;
编译错误就像;
1）运算符>未在类型为customIterator的类型中实现
类型为int
2）operator ==未在类型为customIterator的类型中实现
类型为int
3）operator / not implemented in参数的类型customIterator
类型为int
class customIterator
{ [...] } [...] // compilation errors here .......
std::sort(begin, end, aCompareFunction());
compilation errors are like;
1) operator> not implemented in the type customIterator for arguments
of type int
2) operator== not implemented in the type customIterator for arguments
of type int
3) operator/ not implemented in the type customIterator for arguments
of type int
您可以在全球定义错过的运算符，即
bool运算符>（const customIterator& i1，const customIterator& i2）{return
DistanceOf（i1，i2）> 0; }
bool operator ==（const customIterator& i1，const customIterator& i2）{return
DistanceOf（i1，i2）== 0; }
....
int DistanceOf（const customIterator& i1，const customIterator& i2）
{
//计算迭代器的距离，这可能取决于迭代器内部的
定义
}
希望这有帮助。有问题吗？
// oliver
you can define the missed operators globally, ie
bool operator>(const customIterator&i1, const customIterator&i2) { return
DistanceOf(i1, i2) > 0; }
bool operator==(const customIterator&i1, const customIterator&i2) { return
DistanceOf(i1, i2) == 0; }
....
int DistanceOf(const customIterator&i1, const customIterator&i2)
{
// calculate the distance of your iterators, which may depend on the inner
definition of the iterator
}
Hope this helps. Any questions?
// oliver
* Gr ***** @ nospam.com ：
* Gr*****@nospam.com:
我正在实现一个自定义迭代器（随机访问类型）所以我可以使用
stl算法，例如对我的旧容器进行排序。然而，我正在编译问题。在实现我的customIterator类时，我已经定义了下面的运算符（以及其他运算符，但它们现在不重要，我不认为）。
class customIterator
{/ /
customerIterator& operator *（）const;
int operator-（const customIterator& x）;
int operator-（const contIter& rhs）const
customIterator& operator ++（）;
customIterator operator ++（int）;
customIterator& operator - （）;
customIterator operator - （int）;
customIterator& operator + =（difference_type n）;
customIterator& operator - =（difference_type n）;
customIterator operator +（difference_type rhs）const;
customIterator operator-（difference_type rhs）const;
int& operator []（int n）;
bool operator ==（const customIterator& x）const;
bool operator<（const customIterator& x）const;
}
问题是当我将其中一个迭代器传递给
std :: sort时，我错过了各种类型的运算符，如operator>（int），
operator / （int），operator-（int）。
这些是生成的，因为我平台上的stl :: sort有这样的代码
while（ __last - __first> __stl_threshold）{
或使用类似的表达式;
如果（（__last - __first）/ 2>某事......）
对随机访问迭代器的要求大致是它像指针一样表现为
。
包括比较和减法但是不是除法。
我是否需要提供一个运算符来将我的
customIterator隐式转换为int以进行比较（__last - first>
__stl_threshold）可以是eval uated？
不，你需要定义
std :: ptr_diff operator-（MyIter const& a，MyIter const& b）
现在我只是想通过一个简单的案例
向量的向量来编译这个。
std :: vector< int> vint;
containerWrapper包装器（vint）;
customIterator begin = wrapper.begin（）;
customIterator end = wrapper.end（）;
//编译错误这里.......
std :: sort（开始，结束，aCompareFunction（））;
编译错误就像;
1）运算符>未在类型为customIterator的类型中实现
类型为int
2）operator ==未在类型为customIterator的类型中实现
类型为int
3）运算符/未在类型为customIterator中实现的参数类型为int
I''m implementing a custom iterator (random access type ) so I can use
stl algorithms such as sort on my legacy containers. I''m having
problems compiling however. when implementing my customIterator class I
have defined the operators below (as well as others but they''re not
important right now, I don''t think).
class customIterator
{
customerIterator& operator*() const;
int operator-(const customIterator& x);
int operator-(const contIter& rhs) const
customIterator& operator++();
customIterator operator++(int);
customIterator& operator--();
customIterator operator--(int);
customIterator& operator+=(difference_type n);
customIterator& operator-=(difference_type n);
customIterator operator+(difference_type rhs) const;
customIterator operator-(difference_type rhs) const;
int& operator[](int n);
bool operator==(const customIterator& x) const;
bool operator<(const customIterator& x) const;
}
The problem is when I come to pass one of these iterators into
std::sort, I''m missing all sorts of operators like operator>(int),
operator/(int), operator-(int).
These are being generated because the stl::sort on my platform has code
like this;
while (__last - __first > __stl_threshold) {
or uses expressions like;
if ( (__last - __first)/2 > something... )
The requirements on a random access iterator are, roughly, that it behaves
like a pointer.
That includes comparision and subtraction, but not division.
Do I need to provide an operator for implicit conversion of my
customIterator to an int so that the comparison ( __last - first >
__stl_threshold) can be evaluated?
No, you need to define
std::ptr_diff operator-( MyIter const& a, MyIter const& b )
Right now I''m just trying to get this to compile with a simple case
vectors of ints.
std::vector<int> vint;
containerWrapper wrapper(vint);
customIterator begin = wrapper.begin();
customIterator end = wrapper.end();
// compilation errors here .......
std::sort(begin, end, aCompareFunction());
compilation errors are like;
1) operator> not implemented in the type customIterator for arguments
of type int
2) operator== not implemented in the type customIterator for arguments
of type int
3) operator/ not implemented in the type customIterator for arguments
of type int
我更怀疑你的观点（3）。
-
答：因为它弄乱了人们通常阅读文字的顺序。
问：为什么这么糟糕？
A：热门发布。
问：usenet和电子邮件中最烦人的是什么？
I rather doubt your point (3).
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
" Alf P. Steinbach" <人*** @ start.no>在消息中写道
news：43 **************** @ news.individual.net ...
"Alf P. Steinbach" <al***@start.no> wrote in message
news:43****************@news.individual.net...
* Gr ***** @ nospam.com ：
* Gr*****@nospam.com:
我正在实施一个自定义迭代器（随机访问类型）所以我可以使用
stl算法，例如对我的旧容器进行排序。然而，我正在编译问题。在实现我的customIterator类时，我已经定义了下面的运算符（以及其他运算符，但它们现在不重要，我不认为）。
I''m implementing a custom iterator (random access type ) so I can use
stl algorithms such as sort on my legacy containers. I''m having
problems compiling however. when implementing my customIterator class I
have defined the operators below (as well as others but they''re not
important right now, I don''t think).
[snip]
[snip]
我是否需要提供一个运算符来将我的
customIterator隐式转换为int以进行比较（__last - first>
__stl_threshold ）可以评估？
Do I need to provide an operator for implicit conversion of my
customIterator to an int so that the comparison ( __last - first >
__stl_threshold) can be evaluated?
不，你需要定义
std :: ptr_diff operator-（MyIter const& a，MyIter const& b）
No, you need to define
std::ptr_diff operator-( MyIter const& a, MyIter const& b )
我读过这个吗？在命名空间''std''中定义一些东西？
标准是否允许这样做？
-Mike
Did I read that right? Define something in namespace ''std''?
Is that allowed by the standard?
-Mike
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